With the rapid development of electronic technology, terminals such as mobile phones, IPADs, cameras and the like have become a necessity in people's life, and a photographing function is indispensible for the terminals. With the fast pace of life and improvement of quality of life, requirements on the photographing function are increasingly high. A focusing technology is a key factor for photographing efficiency and photographing quality.
At present, the terminals generally employ phase detection autofocus, contrast detection autofocus, or a mixed focusing method of combining the phase detection autofocus and the contrast detection autofocus to perform intelligent focusing. For the mixed focusing method, a pre-scan is performed via the phase detection autofocus and the contrast detection autofocus to roughly determine a large focusing region, and then in the large focusing region an accurate focusing position is found via an accurate scan.